Hi!
I am a psychology major and have had to take online slp pre reqs so that I can apply for slp fall 2020 master programs. You may already know this, but if you go to each of the schools' websites, you can see exactly which classes are required as pre reqs. I'm not familiar with the requirements for California schools because I'm on the East Coast, but the majority of the schools I am looking at have a lot of overlap between the classes they require. Some common ones are anatomy and physiology, phonetics, intro to audiology, speech and hearing science, & language development. How I went about it, was I found schools that require 6 or less pre reqs that have similar requirements, give or take 1 or 2 classes. I took 2 pre reqs this past summer, and am signed up to take 2 more this spring. When I hear back from schools in March, I will know which classes I need to take this summer based on the school I decide to go to. Some schools even let you take a few pre reqs during your first semester of grad school.
I hope this was helpful/made sense. Let me know if you have more questions.